Jasmine JavaScript Testing Framework Jasmine Custom Matchers and Extensions 3

Question 1

What is the key difference between jasmine.arrayContaining() and jasmine.arrayWithExactContents()?

Accepted Answer

arrayContaining allows extra elements; arrayWithExactContents requires all elements to match exactly

Answer

jasmine.arrayContaining() passes even if the actual array has extra elements, while jasmine.arrayWithExactContents() requires the array to contain exactly the specified elements and no others.

Question 2

How do you define an asymmetric equality tester (custom asymmetric matcher class) in Jasmine?

Accepted Answer

Create a class or object with an asymmetricMatch method

Answer

An asymmetric equality tester is any object that implements an asymmetricMatch(other) method; Jasmine detects this and calls it instead of performing a standard equality check.

Question 3

When jasmine.addMatchers() is called and a custom matcher shares a name with a built-in Jasmine matcher, what happens?

Accepted Answer

The custom matcher overrides the built-in matcher for that scope

Answer

Custom matchers override built-in ones of the same name within the scope where they are registered, allowing temporary overrides of default behavior.

Question 4

What does jasmine.addAsyncMatchers() enable compared to jasmine.addMatchers()?

Accepted Answer

Registers matchers whose compare function returns a Promise

Answer

jasmine.addAsyncMatchers() registers matchers whose compare function can return a Promise, allowing asynchronous checks inside expectAsync() calls.

Question 5

What is the role of the customTesters array that can be passed to matchersUtil.equals()?

Accepted Answer

Allows you to inject custom equality functions that override default object comparison

Answer

Passing customTesters to matchersUtil.equals() injects additional equality functions that Jasmine consults before falling back to its default deep equality logic.

Jasmine JavaScript Testing Framework Practice Test

Jasmine JavaScript Testing Framework Practice Test

Jasmine JavaScript Testing Framework Jasmine Custom Matchers and Extensions 3